1. Field of the Invention
This invention is related to an improvement in the structure of a mixer for new and used plastic materials, and in particular to one which is low in cost and can operate flawlessly.
2. Description of the Prior Art
Referring to FIG. 1, the conventional mixer 1 for and new and used plastic materials includes a closed housing 10 formed with a new and used material inlets 11 and 12 at one side thereof, two pneumatic cylinders 13 and 14 arranged within the housing 10, two pistons 15 and 16 respectively driven by the two pneumatic cylinders 13 and 14 for opening and closing the inlets 11 and 12, and an outlet 17 arranged under the used material outlet 16. The two pneumatic cylinders 13 and 14 are synchronously switched so that the pneumatic cylinder 13 will retract the piston 15 to open the new material inlet 11 while the pneumatic cylinder 14 will push the piston 16 to close the used material inlet 12, and vice versa. Then, the mixed material will be sucked out of the housing 10 by a vacuuming device (not shown).
However, the conventional mixer must be operated by two pneumatic cylinders which are the most expensive components of the mixer thereby making it impossible to reduce the cost. In addition, if there is something wrong with the switching time of the two pneumatic cylinders 13 and 14, the mixing proportion of the new and used materials will be changed thus influencing the properties of the product and therefore producing a lot of waste products.
Therefore, it is an object of the present invention to provide an improvement in the structure of a mixer for new and used plastic materials, which can obviate and mitigate the above-mentioned drawbacks.